The original Korean document needs to be authenticated by the Indonesian Embassy in Korea (Rubber stamp important) it may also need to be done by Indonesian Dept. of Foreign affairs. The embassy will be able to tell you.
Then the wedding certificate needs to be translated into Indonesian by a licenced/recognised translator and again certified as a correct translation by the Embassy/Dept of foreign affairs...
This is not what is stated in the Indonesian Embassy's website (see below) . It seems this subject changed recently , because it looks like that in addition to the marriage certificate + usual documents , now the Embassy requires some documents from Indonesia (seems to be the same documents an Indonesian needs to marry in Indonesia) .
From
https://kemlu.go.id/seoul/pelayanan...n-nikah-tanpa-affidavit-nikah-dari-kbri-seoul (Indonesian Embassy in Seoul/South Korea) - free translation
Marriage Reporting (Without Marriage Affidavit from the Indonesian Embassy in Seoul)
Fill in the Marriage Reporting Application Form at the following link:
https://bit.ly/FormPelaporanNikah
Original Marriage Certificate/ 혼인관계증명서 if married to a Korean citizen, translated into English and notarized.
Original Marriage Certificate/ if married to a non-Korean citizen, translated into English and notarized.
Photocopy of valid Passport/ SPLP.
Photocopy of valid Alien Registration Card/ Residence Card front and back.
Photocopy of Birth Certificate.
Certificate of never been married/already married with proof of divorce certificate, acknowledged by Kantor Kelurahan in Indonesia (original).
Model N1: certificate of marriage (original).
Model N2: certificate of origin (original).
Model N3: letter of consent of the bride and groom (original).
Model N4: certificate of parents (original) and photocopy of parents' KTP.
Model N5: letter of permission from parents for prospective husband/wife (original), or photocopy of death certificate for deceased parents.
If incomplete, add a Certificate of Singleness from the City/Regency Dukcapil Office (original)
Specifically for those married to Korean citizens, Family Census Register (가족관계증명서)/ South Korean Family Card that already contains the name of the Indonesian citizen applicant and has been translated into English and has been legalized by a local Notary.
Photocopy of the passport of the foreign citizen concerned and photocopy of the Identity Card/ Residence Card front and back from the South Korean Government.
Other documents requested by the Indonesian Embassy in Seoul (if needed)
6x4 passport photo of husband and wife with a blue background in 1 frame
FREE.
Procedure:
Report to peduliwni.kemlu.go.id
Come directly to the Indonesian Embassy in Seoul bringing the required documents. The officer will verify whether the documents are complete or not.
After the documents are complete, the officer will interview the husband and wife.